Why “Bounce Testing” should be avoided

Mark Pilate wrote:

Kyle don’t go out of context again.  This definitely ISNT rocket science.   If this threads a mess, it’s due in large part to you sidetracking with straw men.   Again you post irrelevant data about numbers not related to the debate and skirt the salient points about bad proof tests.

Good lord, Mark.  You posted that link, why don't you just tell us what part of it you're referencing?  It's over 100 pages long, it doesn't make a lot of sense for you to expect people to just guess what the heck you're getting at, and then yell at them when they guess wrong.  Just give us the relevant quotes, or provide a page/section number.

2.  Use the proof test principles and logic developed for nylon slings by ASTM.

The ASTM says that slings which are visibly damaged should be retired immediately.  Don't proof test them, don't load them, don't use them.  Their logic is simply not to use a sketchy anchor, not to follow some convoluted field "test" you came up with and trust your life with the results.  This was suggested on page 1, and yet here we are still arguing about your complex test schemes.

back it up beef it up and bail. If you want to bounce by all means bounce because you backed it up and beefed it up and its bomber. if for some reason you have absolutely no choice but to bail from a sketch anchor don't bounce. Down climb under tension if at all possible. if thats not possible and you will freeze to death if you don't bail then bail as soft and smooth as you possibly can with whatever prayers float your boat. the most famous version of that in these parts was the party that tried to climb Gorillas In The Mist after work in the dark because its rarely in. they ended up bailing from a pair of quarks in a smear of ice.. the tools melted out and were collected at the base of the cliff the next day... 

A potential problem with relying on a static 2-body test at the anchor - people seemingly hanging on the anchor, but with their feet resting on slabby terrain. may be putting a lot less weight on the anchor than they think.  Modeling a climber as a block resting on a slope with friction, my math says the PAS tension would follow sin(a) - u * cos(a) (a = angle, u = friction coef).  This drops fast, reaching 1/2 around a = 65 degrees for u=1.  Additionally, I think the relevant angle here is not the slab itself, but the angle of the PAS - even smaller.  On the other hand, terrain encountered during the rappel (between anchors) may well have vertical sections.  So it would be quite easy for 2 people carefully "hanging" on an anchor (but actually having significant weight on their feet) to not even match the weight of 1 person statically hanging on a vertical rappel section.  And that's before even considering the effect of non-pertectly-smooth rappelling.

So, if using a static test, I think it's important for the 2nd person to continue to put significant weight on the anchor as the 1st person rappels.

If it's that close of a deal you  need to leave the  back up in place. That is why the  entire  conversation is silly. 

Nick Goldsmith wrote:

That is why the  entire  conversation is silly. 

Basically it became a pissing contest between two people who get their rocks off arguing many pages ago.

Please post resumes here so I can evaluate your climbing and or mechanical engineering or materials science credibility . Also what does John Largo Long say!

Whenever someone says it’s not rocket science or brain surgery they are downplaying systems complexity. 

Diego Climber wrote:

Whenever someone says it’s not rocket science or brain surgery they are downplaying systems complexity. 

or you just don't understand how complex rocket science and brain surgery are... :)

Diego Climber wrote:

Whenever someone says it’s not rocket science or brain surgery they are downplaying systems complexity. 

You are right.   The complexities here have been evaluated by rocket scientists.  Literally developed by NASA with respect to the details and dangers of “proof testing”.    Simplistic and superficial  analysis as suggested by some here,  and testing oranges thinking they’re just like apples will lead to errors at best, and possibly catastrophe at worse.  

What’s NOT rocket science is following the principles developed out of that and applied directly to nylon slings by dedicated industry engineers…don’t overload, don’t bounce.  

You have no idea what the real condition is of anything you encounter in the field.  No matter what test you do, you’ll never know if it passed with flying colors or just by a hair - so be conservative and limit overloading with high impulse loads.  Because it’s true:   Things like old degraded tat (like Dan’s wood examples above) with a mix of fibers in brittle and ductile failure regimes can potentially survive a quick shock and then be damaged enough to fail under lower extended static loads or a subsequent accidental follow on shock in use.    

Not sure what Largo says on the matter.   

I'm assuming that all of these top climbers taking big FF falls on their gear (quickdraws, etc) are retiring them after use? If they don't, I presume a lot of them die? 

Just wondering... 

Tim Parkin wrote:

I'm assuming that all of these top climbers taking big FF falls on their gear (quickdraws, etc) are retiring them after use? If they don't, I presume a lot of them die? 

Just wondering... 

Oh FFS, nobody is talking about normal gear within useful life.  Stay within context.   Old nasty,  UV and ozone damaged, x number of rope pulls, full of grit, variously loaded under wet/damp conditions, yadda yadda. In situ rap tat.    Know many top climbers taking big FF falls on that?  

The point is that degraded materials with a shit load of variables stacked up, don’t act like the materials you are describing.  Plus the rope limits the impulse.   It’s simple— Just limit shock loading old materials if you need to trust your life to them later.   Should not be a big deal.  

Mark Pilate wrote:

Oh FFS, nobody is talking about normal gear within useful life.  Stay within context.   Old nasty,  UV and ozone damaged, x number of rope pulls, full of grit, variously loaded under wet/damp conditions, yadda yadda. In situ rap tat.    Know many top climbers taking big FF falls on that?  

The point is that degraded materials with a shit load of variables stacked up, don’t act like the materials you are describing.  Plus the rope limits the impulse.   It’s simple— Just limit shock loading old materials if you need to trust your life to them later.   Should not be a big deal.  

Or forget all this bounce test bs on tat and back it up? Or better yet, if there is an extra minute, remove all the tat and do it up fresh? You might save your life, your partner's life and the next person's life too.

Seriously, I don't understand why you're trying to make a dangerous sketchy thing slightly less dangerous and sketchy. Especially when we should be reinforcing the idea that one should be avoiding such circumstances at all cost, if at all possible.

Like, we should have started a tat thread and how to avoid it. A how to recognize tat thread. A how to replace tat thread, on perfect days and what to do when faced with a not so perfect a day. Discussed what other options there are besides tat. Sarted a beautiful tat replacement thread like the beautiful hardware thread. Arguments about tat on trees vs just throwing in some bolts. Grabbed our pitch forks & torches and rid the streets of all the rat-a-tat-tats. Death to all tat!

Leave a sling or two. Leave some draws. Cut your fucking rope if you have to / can do. Do something, just don't rapell on the tat being discussed in this thread. 

I know its a cliché, but you're worth it. Just come home. Don't rappel on tat, especially the kind that Mark is describing to make his point so he can feel good about being right or whatever the hell he's trying to do in this 99% useless topic.

ETA

A tat replacer appreciation thread. The ISCAofTR (International Safe Climbers Association of Tat Removers), the ASCA of tat. Sure, maybe it's a ridiculous idea, but maybe a campaign based on a joke will keep people alive. I'd donate to that cause.

Nobody should walk away from this thread wondering if it's bounce test or not bounce test, on tat. Don't do either, if you want to come home. Backup it up or Replace it. That's the lesson we should be discussing here.

Nathan Doyle wrote:

Nobody should walk away from this thread wondering if it's bounce test or not bounce test, on tat. Don't do either, if you want to come home. Backup it up or Replace it. That's the lesson we should be discussing here.

Nate totally agree.  That was original point and 2/3 of OP —that came out of the Tahquitz accident thread where many suggested bouncing could save lives.  

 This is merely now a grudge match for those that keep coming back to this promoting bouncing on tat or sketchy ice as a good idea and a valid/safe test.  Or use bad logic like “if it can’t support a bounce, you shouldn’t use it”   The bad logic being you don’t know if it passed easy or barely passed at all, and now you’re relying on a potential ticking time bomb assuming it’s now good.  

Or those like Tim above who think if you can do it on your good Draws, should work fine for tat.   How many top climbers buy old used draws off the internet that have been left outside for years and do big FFs on them?  None.  It would be stupid.

This thread is like fly paper for foolishness, and unfortunately I’m now stuck here myself, lol.  My own fault for posting quickly after a weekend pondering the two recent deaths and the many naive responses to it.  

Mark Pilate wrote:

This thread is like fly paper for foolishness, and unfortunately I’m now stuck here myself, lol.  My own fault for posting quickly after a weekend pondering the two recent deaths and the many naive responses to it.  

As originator of the thread, you have the ability to lock it from further replies.

Todd Berlier wrote:

as long as people like you keep responding, yeah.

“People like you” just sounds so aggressive lol

Mark Pilate wrote:

Nate totally agree.  That was original point and 2/3 of OP —that came out of the Tahquitz accident thread where many suggested bouncing could save lives.  

 This is merely now a grudge match for those that keep coming back to this promoting bouncing on tat or sketchy ice as a good idea and a valid/safe test.  Or use bad logic like “if it can’t support a bounce, you shouldn’t use it”   The bad logic being you don’t know if it passed easy or barely passed at all, and now you’re relying on a potential ticking time bomb assuming it’s now good.  

Or those like Tim above who think if you can do it on your good Draws, should work fine for tat.   How many top climbers buy old used draws off the internet that have been left outside for years and do big FFs on them?  None.  It would be stupid.

This thread is like fly paper for foolishness, and unfortunately I’m now stuck here myself, lol.  My own fault for posting quickly after a weekend pondering the two recent deaths and the many naive responses to it.  

Everyone in the Tahquitz thread had already agreed that backing up tat was the solution prior to you starting this thread, so this was just an ill advised ego trip on your behalf to prove you were right in a fringe-case scenario that was being bounced around. And, you've still failed to prove that point by showing you have any credentials to be an authority on the matter, properly referencing verifiable sources and/or testing, and actually coming back around and saying load testing was fine.

Seriously, kill the thread already. 

Ian Lauer wrote:

Seriously, kill the thread already. 

This reminds me of a tactic I used to use when arguing with my little sister by saying ‘You always have to have the last word don’t you’

I’ll kill the thread and let it die the death it deserves as soon as Ian apologizes for being completely clueless, unnecessarily rude, and at the very least, even more trivially argumentative than I have been.

Edit :  and Ian, you said you’d apologize.  just consult basic engineering texts, DuPont and nylon industry information, NASA, ASTM, and rigging industry engineers if you don’t believe me.

Edit2: Taking Marc801c advice and locking it.  If you really have either heartburn for wanting to post, or have some amazing new insight, or a creative flame, pm me and I’ll reopen so you can post.  But it better be good.